1. Field of the Invention
The present invention relates to an electric power tool including a motor-driven shaft for supporting a circular working tool, a locking device for securing the working tool on the shaft, a switch for turning a shaft driving motor on and off a braking device for braking the shaft or the working tool, a safety element having a safety position, in which it actuates the braking device and prevents turning-on of the shaft driving motor, and a release position, in which it deactuates the braking device and provides for turning-on of the shaft driving motor, with the braking device being mechanically connected with the safety element.
2. Description of the Prior Art
An electric power tool of the above-described type includes a coupling connecting the switch with the safety element for preventing an inadvertent actuation of the tool. The braking device serves for rapid braking of the working tool (working shaft) and/or the motor. The braking device is connected with the safety element, e.g., by a linkage. The braking device occupies a non-braking or release position in the release in the position of the safety element, which make the turning-on of the motor possible. When the safety element is in its safety position, the turning-on of the motor cannot be effected, and the braking device is in its braking position.
The above-described electric power tool is disclosed, e.g., in German Publication DE-A1-40 07 030. In the disclosed electric power tool, the braking device, which is mechanically connected with the safety element, is used for braking the working tool. The safety element has safety and release positions. In the release position of the safety element, the electric power tool motor can be turned on, and the braking device is deactuated, i.e., it occupies its non-braking position. In the safety position of the safety element, switching-on of the motor is not possible, and the braking device is actuated, i.e., it occupies its braking position. The braking device includes a braking member rotable about a rotational axis extending parallel to the power tool shaft. The braking member acts on braking drum mounted on the shaft. As a result of frictional forces, which act between the braking member and the braking drum, the motor and the working tool are braked. The actuation of the braking device is effected with an actuation member formed by a linkage including a plurality of articulated elements.
A drawback of the known electric power tool consists in that an inadvertent switching-on of the driving motor is still possible with the tool locking device still occupying its unlocking position.
An object of the invention is to provide means that would reliably prevent an inadvertent switching-on of the power tool motor and that could be reliably and simply actuated.
Another object of the invention is to provide means that would reliably prevent the switching-on of the power tool motor and that could be economically manufactured.